Book excerpt: This volume examines why hospitals collaborate with each other and with other health care actors across borders in Europe. Cross-border hospital collaboration is not a new phenomenon but began to receive increased attention in the first decade of the 21st century in the context of European debates on patient mobility, the impact of European Union (EU) integration on national health systems and the particular situation of border regions. In this context, the role of health care providers stands out: while physically anchored in the health system that funds and regulates them, hospitals in border regions often witness or initiate cross-border movements of patients and health professionals.